While Bordeaux is known for its bold red wines, the region is home to some vineyards growing exclusively white wine grapes. In Sauternes, a blend of Sémillon, Sauvignon Blanc, and Muscadelle grapes work together to create some of the highest-quality sweet wines on the market, thanks to vines infected by noble rot. While the name is peculiar, noble rot, or Botrytis cinerea, is a fungus that infects grapes and produces sweet, high-alcohol wines.

Produced in Sauternes, France, in the southern region of Bordeaux, wines from Château d’Yquem are widely recognized as some of the best sweet white wines in the world. The château sprawls across 113 hectares of vineyard land, with just two grape varieties planted — 75 percent Sémillon and 25 percent Sauvignon Blanc.

The estate has been producing wine for centuries, and its vintages are highly sought after by collectors because of their incredible quality and long lifespan. Due to their high sugar and acid content, wines from Château d’Yquem can keep for well over a century, and they only get better with age. Now that you know the basics, here are 10 more things to know about the iconic wine label.

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It was once owned by the King of England.

While Château d’Yquem is today known as one of the most elite French wine labels, for a lengthy period of time, the estate was in English hands. Throughout the Middle Ages, the Château belonged to the King of England, who also held the title of Duke of Aquitaine. It wasn’t until 1453 that the estate would return to French hands, when King Charles VII acquired the land back under French dominion.

In 1593, the château was taken over by the Sauvage family…

In the 16th century, Jacques de Sauvage, a descendant of nobles, was granted feudal tenure over the château. Over the next few centuries, the Sauvage family built up the château into what it is today. By 1711, the family became the full owners of the estate and solidified a reputation as quality wine producers. In the late 18th century, after the loss of her husband Count Louis Amédée, Françoise Joséphine de Sauvage d’Yquem became the sole head of the château.

Despite being imprisoned twice for her staunch opposition to the French Revolution as a royalist, and being a widow and mother of two at just 20 years old, she was able to maintain a stronghold over the estate. In 1826, Françoise Joséphine, once out of jail, constructed a new wine cellar beneath the château in a move that was considered by many to be wildly audacious. The construction later proved to be fruitful — it allowed for wine to be made in much better conditions and opened up barrel aging at the vineyard. Most winemakers at the time were unable to barrel age wines themselves, instead needing to send them elsewhere to be aged by wine merchants in cellars in Bordeaux. The construction of the 1826 cellar helped to transform Yquem into the international business it is today.

…Until the estate transformed from winemaking hub to military hospital.

In 1918, Château d’Yquem was taken over by military officer Marquis Bertrand de Lur-Saluces. During both World War I and World War II, the estate was transformed into a military hospital where French soldiers were sent to rest and recuperate in the event of an injury. In fact, the chestnut tree that still lives just on the other side of the château’s walls was planted by soldiers. Despite the fact that the estate was used as a hospital, wine production continued during both world wars.

In the 1970s, a perfect storm threatened to close Château d’Yquem.

When Alexandre de Lur-Saluces took over the management of Château d’Yquem from his uncle Bertrand, an extreme inheritance tax, combined with a number of poor vintages and a Bordeaux wine trade crisis, threatened the longevity of the estate. 1972, 1973, and 1974 were exceptionally difficult years for Yquem due to extreme rain and unpredictable weather changes that delayed harvest times and resulted in less-than-ideal production conditions. Thankfully, things turned around in 1975 with a vintage that has been described as “heaven in a glass.” Followed by a number of strong vintages in the 1980s, the château was back on track.

Winemakers at Château d’Yquem follow a rigorous, multi-step process.

Grapes from Château d’Yquem’s vineyard appear in its cellars no more than one hour after they have been harvested. From there, grapes are fermented in new barrels made with stave oak from forests in eastern France. The fermentation process, which stops naturally, typically takes between two and six weeks. Once fermented, these wines, which are produced from grapes harvested on the same day, are aged separately for six to eight months. At this point, a preliminary blend is made, which then undergoes several lab analyses and taste tests. Remaining barrels then undergo an additional aging process for 20 months, after which they are topped off with more wine to fill up any airspace caused by evaporation. At the end of the barrel-aging process, each wine is blindly tasted. The selected wine determines the final blend, which will then go on to be bottled the third winter after its harvest. The remaining “rejected” wines, or blends that were produced in years where no vintage was made, while likely still delectable, are sold anonymously to other producers throughout the region.

Château d’Yquem is in a league of its own.

In 1855, Emperor Napoléon III demanded the creation of a wine classification system for Sauternes wines. As such, the cru system was created as a means of categorizing terroir quality in the region. At the time, only two classifications were put in place — ​premier cru and second cru. However, Château d’Yquem’s wines were rated so highly that the estate earned its very own classification: premier cru supérieur.

There is debate surrounding when Château d’Yquem wines should be drunk.

Vintage wines are Château d’Yquem’s claim to fame, and there are notable differences between the estate’s young and old vintages. Younger vintages will bring forward notes of oak and vanilla, marked by the fruity notes of apricot, mandarin, and tropical fruit. On the other hand, older vintages are much more robust and complex, with notes of prune, stewed fruit, and dried apricot. As such, there is hot debate among wine connoisseurs surrounding when the appropriate time is to open a bottle. While some wine lovers believe the wine can be enjoyed at any stage of life, other connoisseurs consider drinking a young vintage before it has aged for at least 13 years “tantamount to a sacrilege.”

The château also produces Y, a rare wine.

While from the same terroir and vines as the more widely recognized Château d’Yquem, Y is a rare wine label of which only 10,000 bottles are produced annually. Sauvignon Blanc grapes for this label are harvested at the start of the vintage, complemented by Sémillion grapes harvested a few weeks after once they have reached maximum ripeness. The wines are then fermented in a vat room exclusively used for Y label wines, after which they are placed in barrels for the end of fermentation and the aging process.

Château d’Yquem wines have long been beloved by the elite.

Thomas Jefferson, who served as America’s minister to France between 1785 and the French Revolution, developed a deep interest in French wine and, by 1788, Château d’Yquem wines were among some of his favorites. In the early 2000s, a collection of wines was discovered behind a brick wall in Paris, all engraved with the initials “Th.J.” Among the bottles were a number of wines from Château d’Yquem.

The love for the sweet French wines extended to the other side of the globe as well. In 1859, the Great Duke Constantine, brother to the Tsar of Russia, reportedly purchased a barrel of Châeau d’Yquem for 20,000 gold francs, approximately $258,000 in today’s dollars — a wildly unheard of price at the time.

One of the most expensive bottles of wine ever sold was a Château d’Yquem.

In 2011, Christian Vanneque, a former sommelier at La Tour d’Argent in Paris, purchased a bottle of 1811 Château d’Yquem for a cool $117,000. Unlike many wine collectors and large purchasers, Vanneque, at the time of purchase, planned on actually drinking the wine, stating: “It’s not connected to investing. I’m a sommelier. Wine is for drinking.”